Human UBIAD1 prenyltransferase

What it acts on

1. UBIAD1 synthesized MK-4 using GGPP as the isoprenyl side-chain source.

   Human UBIAD1 prenyltransferase → Geranylgeranyl diphosphate / GGPP source_derived_draftungraded
   Experimental context and source evidence

   evidence_span

   {"source_cache": "artifacts/k2-research/25874989.fulltext.txt", "locator": "Exact primary full-text span; zero-based, end-exclusive Unicode character offsets", "file_sha256": "bbd73607ba2570aa383c81c189b29dd19f1cbd7bf7acdd8343ecf3ee7dc5faf8", "start_char": 24159, "end_char": 24399, "text_sha256": "b680e2031495b2fee24a56c799e8cb2f64bbac3c6a3cb0d33592051f2cf41b9f"}

   experimental_model

   Microsomal enzyme assays and mutagenesis

   exposure

   Prenyl donors, reductant, magnesium and lipophilic statins

   limitations

   In-vitro substrate and assay context. Residual microsomal magnesium prevents concluding that synthesis is magnesium-independent; no human supplementation effect was tested.

   nutrient_topic

   Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin K2 / menaquinone family

   organism

   Human UBIAD1 expressed in Sf9 insect cells

   plain_language

   MK-4 production needs a side-chain donor as well as the vitamin K ring.

   primary_references

   [k2-p25874989] Functional characterization of the vitamin K2 biosynthetic enzyme UBIAD1. (2015). https://pubmed.ncbi.nlm.nih.gov/25874989/ DOI: 10.1371/journal.pone.0125737

   tissue_or_cell_type

   Microsomal prenylation

   Vitamin K2: menaquinone forms, carboxylation, recycling and nutrient interactions (2026-09-17) · lines 201–212

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Microsomal enzyme assays and mutagenesis · source_derived_draft · unverified_draft

   ### k2-ggpp-sidechain UBIAD1 synthesized MK-4 using GGPP as the isoprenyl side-chain source. Condition category: normal nutrient_topic: Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. plain_language: MK-4 production needs a side-chain donor as well as the vitamin K ring. organism: Human UBIAD1 expressed in Sf9 insect cells tissue_or_cell_type: Microsomal prenylation experimental_model: Microsomal enzyme assays and mutagenesis limitations: In-vitro substrate and assay context. Residual microsomal magnesium prevents concluding that synthesis is magnesium-independent; no human supplementation effect was tested. exposure: Prenyl donors, reductant, magnesium and lipophilic statins evidence_span: {"source_cache": "artifacts/k2-research/25874989.fulltext.txt", "locator": "Exact primary full-text span; zero-based, end-exclusive Unicode character offsets", "file_sha256": "bbd73607ba2570aa383c81c189b29dd19f1cbd7bf7acdd8343ecf3ee7dc5faf8", "start_char": 24159, "end_char": 24399, "text_sha256": "b680e2031495b2fee24a56c799e8cb2f64bbac3c6a3cb0d33592051f2cf41b9f"} [k2-p25874989] Functional characterization of the vitamin K2 biosynthetic enzyme UBIAD1. (2015). https://pubmed.ncbi.nlm.nih.gov/25874989/ DOI: 10.1371/journal.pone.0125737

   Complete structured claim and evidence

2. Product analysis identified reduced menadione, rather than its quinone form, as an intermediate in UBIAD1-mediated MK-4 formation.

   Human UBIAD1 prenyltransferase → Menadiol / reduced menadione source_derived_draftungraded
   Experimental context and source evidence

   evidence_span

   {"source_cache": "artifacts/k2-research/24085302.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a0197882d517aa2bd4d9b2919e72c588383ad183064f1a2bf8f64f5152d28386", "start_char": 0, "end_char": 1653, "text_sha256": "a0197882d517aa2bd4d9b2919e72c588383ad183064f1a2bf8f64f5152d28386"}

   experimental_model

   Stable-isotope cannulation and recombinant-enzyme product analysis

   exposure

   Oral labeled phylloquinone; MS and NMR analysis

   limitations

   Rat tracing defines a precursor route; no exact human conversion fraction or advice to ingest menadione is inferred.

   nutrient_topic

   Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin K2 / menaquinone family

   organism

   Rats and recombinant UBIAD1

   plain_language

   The precursor must also be in the right redox state.

   primary_references

   [k2-p24085302] Menadione (vitamin K3) is a catabolic product of oral phylloquinone (vitamin K1) in the intestine and a circulating precursor of tissue menaquinone-4 (vitamin K2) in rats. (2013). https://pubmed.ncbi.nlm.nih.gov/24085302/ DOI: 10.1074/jbc.m113.477356

   tissue_or_cell_type

   Intestine, circulation and tissue synthesis

   Vitamin K2: menaquinone forms, carboxylation, recycling and nutrient interactions (2026-09-17) · lines 188–199

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Stable-isotope cannulation and recombinant-enzyme product analysis · source_derived_draft · unverified_draft

   ### k2-reduced-precursor Product analysis identified reduced menadione, rather than its quinone form, as an intermediate in UBIAD1-mediated MK-4 formation. Condition category: normal nutrient_topic: Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The precursor must also be in the right redox state. organism: Rats and recombinant UBIAD1 tissue_or_cell_type: Intestine, circulation and tissue synthesis experimental_model: Stable-isotope cannulation and recombinant-enzyme product analysis limitations: Rat tracing defines a precursor route; no exact human conversion fraction or advice to ingest menadione is inferred. exposure: Oral labeled phylloquinone; MS and NMR analysis evidence_span: {"source_cache": "artifacts/k2-research/24085302.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a0197882d517aa2bd4d9b2919e72c588383ad183064f1a2bf8f64f5152d28386", "start_char": 0, "end_char": 1653, "text_sha256": "a0197882d517aa2bd4d9b2919e72c588383ad183064f1a2bf8f64f5152d28386"} [k2-p24085302] Menadione (vitamin K3) is a catabolic product of oral phylloquinone (vitamin K1) in the intestine and a circulating precursor of tissue menaquinone-4 (vitamin K2) in rats. (2013). https://pubmed.ncbi.nlm.nih.gov/24085302/ DOI: 10.1074/jbc.m113.477356

   Complete structured claim and evidence

3. The tested lipophilic statins inhibited UBIAD1 enzymatic activity in microsomal assays.

   Human UBIAD1 prenyltransferase → Lipophilic statins studied in the UBIAD1 assay source_derived_draftungraded
   Experimental context and source evidence

   evidence_span

   {"source_cache": "artifacts/k2-research/25874989.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a3eb5f4c56ca7a3e70a32c020bba09f4fec5e91048b13a188017bf221f713a68", "start_char": 0, "end_char": 1777, "text_sha256": "a3eb5f4c56ca7a3e70a32c020bba09f4fec5e91048b13a188017bf221f713a68"}

   experimental_model

   Microsomal prenylation assays

   exposure

   Lipophilic statin exposure

   limitations

   Direct in-vitro inhibition; neither a clinical statin-to-K2-deficiency cascade nor a K2 supplementation indication is established.

   nutrient_topic

   Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin K2 / menaquinone family

   organism

   Human UBIAD1 expressed in insect cells

   plain_language

   A drug-enzyme interaction is searchable without assuming it causes deficiency at usual treatment exposure.

   primary_references

   [k2-p25874989] Functional characterization of the vitamin K2 biosynthetic enzyme UBIAD1. (2015). https://pubmed.ncbi.nlm.nih.gov/25874989/ DOI: 10.1371/journal.pone.0125737

   tissue_or_cell_type

   MK-4 synthesis

   Vitamin K2: menaquinone forms, carboxylation, recycling and nutrient interactions (2026-09-17) · lines 851–862

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Microsomal prenylation assays · source_derived_draft · unverified_draft

   ### k2-ubiad-statin-context The tested lipophilic statins inhibited UBIAD1 enzymatic activity in microsomal assays. Condition category: normal nutrient_topic: Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A drug-enzyme interaction is searchable without assuming it causes deficiency at usual treatment exposure. organism: Human UBIAD1 expressed in insect cells tissue_or_cell_type: MK-4 synthesis experimental_model: Microsomal prenylation assays limitations: Direct in-vitro inhibition; neither a clinical statin-to-K2-deficiency cascade nor a K2 supplementation indication is established. exposure: Lipophilic statin exposure evidence_span: {"source_cache": "artifacts/k2-research/25874989.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a3eb5f4c56ca7a3e70a32c020bba09f4fec5e91048b13a188017bf221f713a68", "start_char": 0, "end_char": 1777, "text_sha256": "a3eb5f4c56ca7a3e70a32c020bba09f4fec5e91048b13a188017bf221f713a68"} [k2-p25874989] Functional characterization of the vitamin K2 biosynthetic enzyme UBIAD1. (2015). https://pubmed.ncbi.nlm.nih.gov/25874989/ DOI: 10.1371/journal.pone.0125737

   Complete structured claim and evidence

4. UBIAD1 G186R significantly impaired both MK-4 biosynthesis and vitamin K-dependent reporter carboxylation.

   Human UBIAD1 prenyltransferase → Vitamin K-dependent protein gamma-carboxylation source_derived_draftungraded
   Experimental context and source evidence

   availability_state

   machinery_impairment Imported condition classification; unverified.

   evidence_span

   {"source_cache": "artifacts/k2-research/34813684.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f533947abd5f26101d1bf1e2548d37b98d16bb72c470dcdfaf2b2f2625c5e206", "start_char": 0, "end_char": 1777, "text_sha256": "f533947abd5f26101d1bf1e2548d37b98d16bb72c470dcdfaf2b2f2625c5e206"}

   experimental_model

   CRISPR reporter cells with UBIAD1 variants

   exposure

   UBIAD1 N102S, G186R and other variants

   limitations

   Cell-specific residual activity differs between variants; a UBIAD1 mutation is not automatically global vitamin K failure.

   nutrient_topic

   Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin K2 / menaquinone family

   organism

   Human HEK293 reporter cells

   plain_language

   A different variant impaired both supply and use in the same assay.

   primary_references

   [k2-p34813684] Naturally occurring UBIAD1 mutations differentially affect menaquinone biosynthesis and vitamin K-dependent carboxylation. (2022). https://pubmed.ncbi.nlm.nih.gov/34813684/ DOI: 10.1111/febs.16291

   tissue_or_cell_type

   MK-4 production and protein carboxylation

   trigger_kind

   machinery_impairment Imported condition classification; unverified.

   Vitamin K2: menaquinone forms, carboxylation, recycling and nutrient interactions (2026-09-17) · lines 253–264

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · CRISPR reporter cells with UBIAD1 variants · source_derived_draft · unverified_draft

   ### k2-ubiad1-g186r UBIAD1 G186R significantly impaired both MK-4 biosynthesis and vitamin K-dependent reporter carboxylation. Condition category: machinery_impairment nutrient_topic: Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A different variant impaired both supply and use in the same assay. organism: Human HEK293 reporter cells tissue_or_cell_type: MK-4 production and protein carboxylation experimental_model: CRISPR reporter cells with UBIAD1 variants limitations: Cell-specific residual activity differs between variants; a UBIAD1 mutation is not automatically global vitamin K failure. exposure: UBIAD1 N102S, G186R and other variants evidence_span: {"source_cache": "artifacts/k2-research/34813684.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f533947abd5f26101d1bf1e2548d37b98d16bb72c470dcdfaf2b2f2625c5e206", "start_char": 0, "end_char": 1777, "text_sha256": "f533947abd5f26101d1bf1e2548d37b98d16bb72c470dcdfaf2b2f2625c5e206"} [k2-p34813684] Naturally occurring UBIAD1 mutations differentially affect menaquinone biosynthesis and vitamin K-dependent carboxylation. (2022). https://pubmed.ncbi.nlm.nih.gov/34813684/ DOI: 10.1111/febs.16291

   Complete structured claim and evidence

5. UBIAD1-targeted siRNA inhibited labeled MK-4 formation in human cells.

   Human UBIAD1 prenyltransferase → Menaquinone-4 biosynthesis source_derived_draftungraded
   Experimental context and source evidence

   availability_state

   machinery_impairment Imported condition classification; unverified.

   evidence_span

   {"source_cache": "artifacts/k2-research/20953171.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3", "start_char": 0, "end_char": 2006, "text_sha256": "b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3"}

   experimental_model

   Gene knockdown, heterologous expression, isotope conversion and NMR

   exposure

   Labeled vitamin K precursors, UBIAD1 knockdown and expression

   limitations

   Identifies a biosynthetic enzyme, not a clinical requirement to supplement MK-4. K1-derived MK-4 synthesis does not make humans independent of external vitamin K precursors.

   nutrient_topic

   Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin K2 / menaquinone family

   organism

   Human UBIAD1 in human and insect-cell systems; mouse localization

   plain_language

   A synthesis defect is different from simply eating little K2.

   primary_references

   [k2-p20953171] Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme. (2010). https://pubmed.ncbi.nlm.nih.gov/20953171/ DOI: 10.1038/nature09464

   tissue_or_cell_type

   MK-4 synthesis

   trigger_kind

   machinery_impairment Imported condition classification; unverified.

   Vitamin K2: menaquinone forms, carboxylation, recycling and nutrient interactions (2026-09-17) · lines 149–160

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Gene knockdown, heterologous expression, isotope conversion and NMR · source_derived_draft · unverified_draft

   ### k2-ubiad1-knockdown UBIAD1-targeted siRNA inhibited labeled MK-4 formation in human cells. Condition category: machinery_impairment nutrient_topic: Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A synthesis defect is different from simply eating little K2. organism: Human UBIAD1 in human and insect-cell systems; mouse localization tissue_or_cell_type: MK-4 synthesis experimental_model: Gene knockdown, heterologous expression, isotope conversion and NMR limitations: Identifies a biosynthetic enzyme, not a clinical requirement to supplement MK-4. K1-derived MK-4 synthesis does not make humans independent of external vitamin K precursors. exposure: Labeled vitamin K precursors, UBIAD1 knockdown and expression evidence_span: {"source_cache": "artifacts/k2-research/20953171.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3", "start_char": 0, "end_char": 2006, "text_sha256": "b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3"} [k2-p20953171] Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme. (2010). https://pubmed.ncbi.nlm.nih.gov/20953171/ DOI: 10.1038/nature09464

   Complete structured claim and evidence

6. Mutational analysis assigned conserved domain IV to magnesium/isoprenyl-side-chain interactions.

   Human UBIAD1 prenyltransferase → Mg2+ source_derived_draftungraded
   Experimental context and source evidence

   evidence_span

   {"source_cache": "artifacts/k2-research/25874989.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a3eb5f4c56ca7a3e70a32c020bba09f4fec5e91048b13a188017bf221f713a68", "start_char": 0, "end_char": 1777, "text_sha256": "a3eb5f4c56ca7a3e70a32c020bba09f4fec5e91048b13a188017bf221f713a68"}

   experimental_model

   Microsomal enzyme assays and mutagenesis

   exposure

   Prenyl donors, reductant, magnesium and lipophilic statins

   limitations

   In-vitro substrate and assay context. Residual microsomal magnesium prevents concluding that synthesis is magnesium-independent; no human supplementation effect was tested.

   nutrient_topic

   Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin K2 / menaquinone family

   organism

   Human UBIAD1 expressed in Sf9 insect cells

   plain_language

   Magnesium-related enzyme chemistry is recorded separately from a claim that oral magnesium improves K2 status.

   primary_references

   [k2-p25874989] Functional characterization of the vitamin K2 biosynthetic enzyme UBIAD1. (2015). https://pubmed.ncbi.nlm.nih.gov/25874989/ DOI: 10.1371/journal.pone.0125737

   tissue_or_cell_type

   Microsomal prenylation

   Vitamin K2: menaquinone forms, carboxylation, recycling and nutrient interactions (2026-09-17) · lines 214–225

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Microsomal enzyme assays and mutagenesis · source_derived_draft · unverified_draft

   ### k2-ubiad1-magnesium-site Mutational analysis assigned conserved domain IV to magnesium/isoprenyl-side-chain interactions. Condition category: normal nutrient_topic: Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium-related enzyme chemistry is recorded separately from a claim that oral magnesium improves K2 status. organism: Human UBIAD1 expressed in Sf9 insect cells tissue_or_cell_type: Microsomal prenylation experimental_model: Microsomal enzyme assays and mutagenesis limitations: In-vitro substrate and assay context. Residual microsomal magnesium prevents concluding that synthesis is magnesium-independent; no human supplementation effect was tested. exposure: Prenyl donors, reductant, magnesium and lipophilic statins evidence_span: {"source_cache": "artifacts/k2-research/25874989.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "a3eb5f4c56ca7a3e70a32c020bba09f4fec5e91048b13a188017bf221f713a68", "start_char": 0, "end_char": 1777, "text_sha256": "a3eb5f4c56ca7a3e70a32c020bba09f4fec5e91048b13a188017bf221f713a68"} [k2-p25874989] Functional characterization of the vitamin K2 biosynthetic enzyme UBIAD1. (2015). https://pubmed.ncbi.nlm.nih.gov/25874989/ DOI: 10.1371/journal.pone.0125737

   Complete structured claim and evidence

7. UBIAD1 N102S retained about 82% of MK-4 biosynthetic activity and did not impair reporter carboxylation.

   Human UBIAD1 prenyltransferase → Vitamin K-dependent protein gamma-carboxylation source_derived_draftungraded
   Experimental context and source evidence

   availability_state

   machinery_impairment Imported condition classification; unverified.

   evidence_span

   {"source_cache": "artifacts/k2-research/34813684.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f533947abd5f26101d1bf1e2548d37b98d16bb72c470dcdfaf2b2f2625c5e206", "start_char": 0, "end_char": 1777, "text_sha256": "f533947abd5f26101d1bf1e2548d37b98d16bb72c470dcdfaf2b2f2625c5e206"}

   experimental_model

   CRISPR reporter cells with UBIAD1 variants

   exposure

   UBIAD1 N102S, G186R and other variants

   limitations

   Cell-specific residual activity differs between variants; a UBIAD1 mutation is not automatically global vitamin K failure.

   nutrient_topic

   Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin K2 / menaquinone family

   organism

   Human HEK293 reporter cells

   plain_language

   A partial synthesis change did not automatically disable the downstream reaction.

   primary_references

   [k2-p34813684] Naturally occurring UBIAD1 mutations differentially affect menaquinone biosynthesis and vitamin K-dependent carboxylation. (2022). https://pubmed.ncbi.nlm.nih.gov/34813684/ DOI: 10.1111/febs.16291

   tissue_or_cell_type

   MK-4 production and protein carboxylation

   trigger_kind

   machinery_impairment Imported condition classification; unverified.

   Vitamin K2: menaquinone forms, carboxylation, recycling and nutrient interactions (2026-09-17) · lines 240–251

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · CRISPR reporter cells with UBIAD1 variants · source_derived_draft · unverified_draft

   ### k2-ubiad1-n102s UBIAD1 N102S retained about 82% of MK-4 biosynthetic activity and did not impair reporter carboxylation. Condition category: machinery_impairment nutrient_topic: Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A partial synthesis change did not automatically disable the downstream reaction. organism: Human HEK293 reporter cells tissue_or_cell_type: MK-4 production and protein carboxylation experimental_model: CRISPR reporter cells with UBIAD1 variants limitations: Cell-specific residual activity differs between variants; a UBIAD1 mutation is not automatically global vitamin K failure. exposure: UBIAD1 N102S, G186R and other variants evidence_span: {"source_cache": "artifacts/k2-research/34813684.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "f533947abd5f26101d1bf1e2548d37b98d16bb72c470dcdfaf2b2f2625c5e206", "start_char": 0, "end_char": 1777, "text_sha256": "f533947abd5f26101d1bf1e2548d37b98d16bb72c470dcdfaf2b2f2625c5e206"} [k2-p34813684] Naturally occurring UBIAD1 mutations differentially affect menaquinone biosynthesis and vitamin K-dependent carboxylation. (2022). https://pubmed.ncbi.nlm.nih.gov/34813684/ DOI: 10.1111/febs.16291

   Complete structured claim and evidence

8. Human UBIAD1 expression supported conversion of labeled vitamin K precursors to MK-4, identified by deuterium NMR.

   Human UBIAD1 prenyltransferase → Menaquinone-4 biosynthesis source_derived_draftungraded
   Experimental context and source evidence

   evidence_span

   {"source_cache": "artifacts/k2-research/20953171.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3", "start_char": 0, "end_char": 2006, "text_sha256": "b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3"}

   experimental_model

   Gene knockdown, heterologous expression, isotope conversion and NMR

   exposure

   Labeled vitamin K precursors, UBIAD1 knockdown and expression

   limitations

   Identifies a biosynthetic enzyme, not a clinical requirement to supplement MK-4. K1-derived MK-4 synthesis does not make humans independent of external vitamin K precursors.

   nutrient_topic

   Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin K2 / menaquinone family

   organism

   Human UBIAD1 in human and insect-cell systems; mouse localization

   plain_language

   Cells have an enzyme that can make MK-4 from vitamin K precursors.

   primary_references

   [k2-p20953171] Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme. (2010). https://pubmed.ncbi.nlm.nih.gov/20953171/ DOI: 10.1038/nature09464

   tissue_or_cell_type

   MK-4 synthesis

   Vitamin K2: menaquinone forms, carboxylation, recycling and nutrient interactions (2026-09-17) · lines 136–147

   AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Gene knockdown, heterologous expression, isotope conversion and NMR · source_derived_draft · unverified_draft

   ### k2-ubiad1-synthesis Human UBIAD1 expression supported conversion of labeled vitamin K precursors to MK-4, identified by deuterium NMR. Condition category: normal nutrient_topic: Vitamin K2 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Cells have an enzyme that can make MK-4 from vitamin K precursors. organism: Human UBIAD1 in human and insect-cell systems; mouse localization tissue_or_cell_type: MK-4 synthesis experimental_model: Gene knockdown, heterologous expression, isotope conversion and NMR limitations: Identifies a biosynthetic enzyme, not a clinical requirement to supplement MK-4. K1-derived MK-4 synthesis does not make humans independent of external vitamin K precursors. exposure: Labeled vitamin K precursors, UBIAD1 knockdown and expression evidence_span: {"source_cache": "artifacts/k2-research/20953171.abstract.txt", "locator": "Exact primary indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3", "start_char": 0, "end_char": 2006, "text_sha256": "b8786e664d3b32db7b0cca72c710e24f1546e14f0a69c031908400731174cea3"} [k2-p20953171] Identification of UBIAD1 as a novel human menaquinone-4 biosynthetic enzyme. (2010). https://pubmed.ncbi.nlm.nih.gov/20953171/ DOI: 10.1038/nature09464

   Complete structured claim and evidence